In the United States, about 10% of the population will suffer from back pain sometime in the next year. This occurrence is more than any other injury or disease except for the common cold and flu. About one-third of those suffering from back pain will not recover and will live with persistent, disabling symptoms. These numbers are cumulative year after year.
One cause of pain in the back and lower extremities is caused by an injury or some other damage to the sacroiliac joint (“SI joint”). The SI joint is a firm, small joint that lies at the junction of the spine and the pelvis and it plays a major role in transferring the load of a person's upper body to the lower body. A person has two SI Joints one on the right side of the pelvis and the other on the left side. FIG. 1 illustrates a model of an SI joint, showing the SI joint 30 located between the sacrum 10 and the ilium 30. The SI joint, like other joints, is lined with cartilage and other connective tissue to prevent bone on bone contact between the sacrum and the ilium. This cartilage may become damage or degraded (e.g., because of osteoarthritis). Without the spongy cartilaginous cushion, joint bones begin to rub against each other when at rest and during movement causing a substantial amount of pain. Therefore, one option to treat this type of pain is to join rubbing portions of bone together so that this painful friction does not occur.
Various methods for treating SI joint exist, but are not widely used. For example, FIG. 2 shows a method wherein screws 50 are surgically installed through ilium 20, across the SI joint 30, and into the sacrum 10. Other existing methods include installation of a metal plate to stabilize the SI joint. Most of these methods have substantial risks, result in substantial discomfort to the patient, require an open, invasive surgical procedure that requires a long recovery time and/or has a low success rate in eliminating or reducing pain resulting from SI joint problems.